: I just found a box of my cast .722" balls cast of Wheelweights. These were cast in the J.Tanner mould I have, which is marked .725". They weigh 553 gr. in WW metal. Also, I found a few 10 bore ball bearings at .775" in diameter. 10 bore is actually .774", so .775 is too large even for 10 bore. These weigh only 492.6gr.
: I expect a 12 bore ball bearing will be between 400gr. to to 430gr., compared to the 553gr. weight of the WW ball. Too, one must be careful the steel ball does not touch the wall of the barrel as it will score the steel as they are very hard indeed, much harder than the barrel steel. The ball bearings were actually heavier than I thought they'd be, but since we can make cast(& harden if necessary) W.W. balls harder than we actually need, I see no reason for shooting steel ones. Each to his own, though as this is all experimentation at it's best.
; Some time ago, in 1986 when we put my 14 bore rifle together, I fired a wheelweight ball at a concrete block at 75 yards range. The block was 3" thick, x 18" x 10" wide. The 466gr. round ball was loaded with 165gr. 2F powder. At the shot, the concrete block disintegrated into chunks smaller than 5" along with a mass of concrete dust in the air. I have since lost that ball, but recall vividly what it looked like -It looked like a normaly expanded pure lead ball from a dirt backstop. I also recall the ball lost less than 100 gr. weight & was way over 1" in diameter. It was found lying amidst the rubble of the block.